Domestic Hot Water is warm!

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Old 12-16-11, 12:56 PM
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Domestic Hot Water is warm!

I have what I think is called an 'indirect' DHW system. The water is stored in a tank and a Taco cartridge circulator moves water through the boiler coil. But I am only getting semi warm water lately. I replaced the cartridge for the Taco but the old cartridge looked fine(previous replaced cartridges have shown wear and tear on the impeller with broken fins, etc) and with the new cartridge things have not improved. The copper pipe coming from the furnace/boiler to the bottom of the water tank is super hot but the pipe coming out of the bottom of the tank to the circulator pump is barely warm, and sometimes outright cold- same for the pipe from the outlet side of the circulator back to the coil. The pipe on the top of the tank that supplies the house is also just warm, of course.The system is pretty old. The fact that the feed in side pipes are so hot, while the feed out sides are warm or cold makes me wonder what is going on- a clog? Thanks for any help!
 
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Old 12-16-11, 04:07 PM
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previous replaced cartridges have shown wear and tear on the impeller with broken fins, etc)
After how long in service? That's sorta unusual...

What's the make/model of the 'indirect' ? also the boiler make/model ?

Is the water heater piped to the same piping that connects to the heating for the home? Or is it piped to a pair of pipes that are coming out of a plate with a bunch of bolts holding it to the boiler?

Pictures might help here...

If you can take in focus, well lighted, large enough for old dudes to see photos of the system and piping, set up a FREE account at Image hosting, free photo sharing & video sharing at Photobucket and upload the pics there. Come back here and place a link to your PUBLIC album for us to view.
 
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Old 12-16-11, 09:45 PM
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Thanks for the reply NJ trooper ... The deteriorated Taco impeller was in service a long time and Taco told me that the material they had been using on that model did have some failures and 'crumbling' of the plastic in certain type of water. The new cassette with the black plastic type impeller shows no decay or wear so I think that issue is fine. The motor housing gets warm and you can feel vibration though I have no idea if it is actually pumping. Except that I do have some degree of warm water so it must be moving something I guess.


Originally Posted by NJ Trooper View Post
After how long in service? That's sorta unusual...

What's the make/model of the 'indirect' ? also the boiler make/model ?

Is the water heater piped to the same piping that connects to the heating for the home? Or is it piped to a pair of pipes that are coming out of a plate with a bunch of bolts holding it to the boiler?
I have the plate with bunch of bolts- the dhw coil I assume? So I guess I dont have an indirect system I have a booster/buffer tank?

The boiler is a Dunkirk Blue Circle No. 615( 1.8 gph, PSI 30, 137300 BTU!!!??) It is old. My dad, who worked on furnaces would have salvaged it from the company and put it in when he built the house in 77)

The water tank is a Lovekin-Tragesser AG30. I noticed it says it has a magnesium anode to limit corrosion and this should be checked every 2 years- I know this has not been done in ages- maybe the tank is clogged completely? Wouldnt that just mean decreased flow and not lower temp?

Pictures might help here...

Pictures by Horse985 - Photobucket

I posted 5 pictures with descriptions that I hope make sense. The lack of full hot water is a come and go problem, sometimes it seems to 'fix itself'. Other times I have replaced that Taco cartridge but not sure that was the actual cause. I do have acid my dad used to use on the coil. And I am skilled enough to sweat fit and redo all those pipes and valves BUT, as you can see the fittings at the base of the water tank are just a mess and I am afraid if I mess with anything they will give me problems and/or the tank is shot or will fail.

When I had the Taco off to switch in the new cartridge I notice water flowing back and down from the cold side- somehow getting past that check valve. But since the taco runs continuously I dont see how that could result in the cold back feeding.

Also with the taco off I opened the valve on the tank side to see what would flow from the tank and the flow was very slow- this didnt seem right?

Glancing at new tanks online the costs seem pretty high, like 6-700 or more so I am hoping I can find some fix that I can squeek through the winter on until we decide our long term plans for this house.

Thanks a million.
 

Last edited by NJT; 12-17-11 at 07:50 AM.
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Old 12-17-11, 07:57 AM
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Yes, that's a 'booster' tank.

I can't tell if it is or not, but the pump should be a bronze one for that application.

There are a few leaking connections as you've pointed out. Not the valves, but those ones with the white crud growing on them... those are slow leaks.

My feeling is that the coil in the boiler is 'limed up'... there isn't a coil in the booster tank, that's all potable connections. It's possible that the pipe going in is hot, and coming out is cool, because when the hot goes in, it immediately floats to the top, and the return back to the coil from the tank is cool/cold because it's drawing from the bottom of the tank.

If the coil is limed up, it just doesn't have the capacity to support the tank and that's why the water is cool.

You say that the pump runs 24/7 ? I wonder why there's no aquastat on the tank and a relay running the pump?

Yeah, you touch those connections and you may find yourself in replacement mode... but they could spring a bigger leak at any time I guess...

Love the quadruplet drip pans under the valves!
 
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Old 12-17-11, 08:09 AM
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That hot water tank looks very old and very tired. It'll be interesting to hear if anyone has a quicky solution to your hot water woes.

I hear you on not wanting to spend a lot of coin when you aren't sure about your long-term plans in the home, BUT I'd still seriously consider replacing the tank. If you put the home up for sale, that old tank will in all likelihood come up as a red flag on an inspector's report. Which means you'll be dealing with the issue sooner or later. So you might as well install a new tank as soon as practical so you can at least enjoy the benefits of it while you are still in the home.

Just my layman's opinion.
 
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Old 12-17-11, 10:42 AM
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Thanks Rockledge and NJ Trooper for the replies and thanks NJ for the edit to clean up my post- I couldn't figure out how to highlight quotes.

Sounds like I have to attempt to de-lime the coil first and foremost and then also consider a tank replacement and new plumbings.

A question:

It is getting pretty cold finally here in MA. If I gather the parts and get working on the problems but dont complete the work before sundown( errors and delays seem guaranteed for me) can I run the furnace for HEAT even if the DHW coil is empty and/or no water is being circulated through it?

If doing that is safe then I have a margin of error to do all the tasks over a few days and not the rush to get it all done and right before the house gets cold; it seems I always have to run to buy some part that I forgot, bought wrong or did not anticipate needing etc.

The pump is bronze by the way and there is an aquastat/relay all in place from before- I do not know why it is set to run 24/7 now.

If, maybe a big if, I can get the coil de-limed OK and I wanted to just switch to a tankless coil set up is there any way to guess from the Dunkirk Model info what sort of hot water volume I would get?

It is just me and the dog living here for now- no dishwasher, no washing machine and the dog does not shower.

For a tankless coil system I would need the two shut off and clean outs already installed from the de-lime and then a tempering valve prior to supply for the house- what about a pressure relief valve? Where would I place that?

Given that the furnace usually is in use until Spring I was hoping I could do this and forgo even an aquastat for the tankless coil, then come warm weather either add a bolt on stat? or go ahead and add a new tank or another type of water heater.

Anyone know where I can find a good diagram of the plumbing for a tankless coil set-up?

Thanks
 
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Old 12-17-11, 10:56 AM
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Whats your budget for a complete system boiler and all?

I am an advocate of keeping old boilers but with all your leaks, and age of the unit the money an repair may be better spent on replacing everything.

I believe if you find the right contractor it can be done 6-8K range.

Just my opinion.

Mike NJ
 
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Old 12-17-11, 11:30 AM
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can I run the furnace for HEAT even if the DHW coil is empty and/or no water is being circulated through it?
Yes. The coil won't be damaged by having no water in it, and the boiler water is completely separate from the domestic water.

I do not know why it is set to run 24/7 now.
Could be the thinking was that as the coil began to get limed up, running the pump 24/7 would make more hot water? Or maybe that if the water were kept running it might slow down the buildup of the minerals? dunno...

By the way, there may well be a whole lotta mineral buildup in the bottom of that tank as well...

I wanted to just switch to a tankless coil set up is there any way to guess from the Dunkirk Model info what sort of hot water volume I would get?
Brand name doesn't really matter, they are all pretty much the same. They all are pi55 p00r ways of making domestic hot water. If yer really lucky, you MIGHT get say 1.5 - 2 GPM of hot water... maybe... I wouldn't recommend the effort, but if it's all ya got, you could probably make it do.

what about a pressure relief valve? Where would I place that?
I don't think you need one. There's not enough volume of water in that coil to cause any real problem with over pressure as the water heats. Some diagrams do show them, but I can't recall seeing one on a straight tankless setup ever. If there is a CHECK VALVE in the cold supply line feeding the coil, you MAY need one. I'm gonna ask Mike to provide more info if he can.

a tempering valve prior to supply for the house
Yes, recommended. This will also improve the odds of getting adequate hot water supply to the home because the flow through the coil slows down due to the 'mixing' of the hot from the coil with the cold from house.

Anyone know where I can find a good diagram of the plumbing for a tankless coil set-up?
I just looked around some... and didn't find anything useful...

Basically, you bring the cold in to a tee... one port on the tee goes to the coil, the other port on the tee goes to the cold inlet of the mixing valve. The hot out of the coil goes to the hot inlet of the mixing valve, and of course the tempered out of the mixing valve goes to the domestic hot in the home.
 
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Old 12-17-11, 11:39 AM
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go ahead and add a new tank or another type of water heater.
If you go to a true indirect, don't forget that it can be used with any new boiler that might get installed later.

You could probably come up with a way to use an inexpensive electric water heater as a storage tank...

Install a TEE where the relief valve is installed and run the hot out of the boiler coil into the side port of the tee, reinstall the relief valve in the other port.

Install a TEE where the drain valve is and pump the cooler water from the bottom of the tank to the cold inlet of the boiler coil.

I believe you could wire a 'strap-on' aquastat to the hot outlet of the tank to run the pump...

You could simply not wire up the electric elements, or wire them for backup use... or shut the boiler off in the summer and use the electric only then...

This would be an inexpensive, but probably only last 5 6 7 years solution.
 
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Old 12-17-11, 12:55 PM
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Thanks everyone for the help and ideas. It looks like everything hinges on if the coil can be de-limed enough. If not I suppose it will need to be replaced and I suspect that task may be beyond my skills. I think I will call my heating company and see what sort of estimate they come up with for replacing the whole DHW set up itself. And pending that decide if I want to try and tackle doing a tankless coil with cheapo electric tank as buffer/summer unit hybrid routine. I cant swing the entire boiler replacement too right now.
 
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Old 12-17-11, 04:39 PM
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Originally Posted by NJ Trooper View Post
If you go to a true indirect, don't forget that it can be used with any new boiler that might get installed later.
That's how it went at my place. Several years ago I plumbed in an Amtrol Boilermate indirect, hooking it up to an old oil boiler and piping that was in place. (It wasn't too difficult of a job - I just took my time and followed the I/O manual to the letter). Well, the increase in hot water comfort in the house only went up about %1000! Night and day difference. I had almost forgotten what a 30 minute hot soaker shower felt like.

A few years ago, when I switched over to a new NG-fired boiler (with the help and guidance of a relative who is a pro), hooking up the Amtrol indirect to the new boiler was the easiest part of the job. Heck, it took longer to wire it up then it did to plumb it in.
 
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Old 12-17-11, 05:01 PM
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Well, the increase in hot water comfort in the house only went up about %1000!
Rock, tell us how much your fuel bills went down?
 
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Old 12-17-11, 06:03 PM
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Originally Posted by NJ Trooper View Post
Rock, tell us how much your fuel bills went down?
Hi Troop,

It's not that easy to quantify the savings from the early days, right after I first installed the Amtrol indirect, because the old oil burner was a warm-start w/coil which I decided to keep as a warm start (I know, I should get 20 lashes for that!). But the old unit (50+ years old) had had issues with leaky coil gaskets in the past and I thought that switching to a cold-start would probably be an invitation to more problems. I bounced it off a few knowledgeable people who agreed with me that I should probably be safer than sorrier. So the bottom line is that, for the first 2+ years, the Amtrol indirect essentially ran off the low limit of the old boiler's triple aqaustat (you might recall the pics of it I linked to in another thread). Quite frankly, at that point, I was so thrilled to have steady, consistent hot water in the house that I wasn't all that worried about the less-than-ideal setup.

But fast forward a little bit to when the new Utica MGB got installed. That is when I really noticed some savings! Being a more modern and efficient cold-start, the H/HW system with the new boiler installed is now really able to operate to it's best design. The boiler only runs when it has to. The indirect is now wired for priority (couldn't do that before), as well.

In a nutshell: Before I had oil bills for the house in the $2,500+/yr range. My gas bill last year was around $1,800. Which turns out to be what, a 28% savings compared to before? I realize there are other variables to consider, such as "degree days" and such, but those savings are real - and substantial.
 
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Old 12-17-11, 06:40 PM
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where would an indirect get its water from- the coil that used to be for the DHW or is the water supply that serves the heat would get split into two zones?
 
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Old 12-17-11, 07:02 PM
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It's treated like another heating zone. There is a coil inside the indirect tank that carries the hot boiler water to heat the domestic hot water. They work great!
 
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Old 12-17-11, 11:37 PM
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Originally Posted by Horse9 View Post

A question:

It is getting pretty cold finally here in MA. If I gather the parts and get working on the problems but dont complete the work before sundown( errors and delays seem guaranteed for me) can I run the furnace for HEAT even if the DHW coil is empty and/or no water is being circulated through it?
Sorry I missed this. What you can do once you decide to take the plunge for a new tank is to utilize some Sharkbite end stops. You can use them to "plug" the supply and return lines to/from the tank until you are ready to permanently connect up the new tank. All that's necessary is a cheap "disconnect" clip to remove the Sharkbite end stops.
 
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